Methanol extraction of lowtemperature tar



Oct. 20,- 1964 M. D. KULIK 3,153,626

METHANOL EXTRACTION oF Low-TEMPERATURE TAR 2 Sheets-Sheet 1 Filed March 50. 1960 lNvEN'roR. METRO KIM/l( Oct. 20, 1964 M D, KULlK 3,153,626

METHANOL EXTRACTION OF' LOW-TEMPERATURE TAR METRO 0. KUL/l( United States Patent O 3,153,626 METHANL EXTRACTHN F LW- TEMPERAT TAR Metro D. Kulik, Pittsburgh, Pa., assigner to Consolidation Coal Company, Pittsburgh, Pa., a corporation oi Pennsylvania Filed Mar. 30, 1964i, Ser. No. 1S,694 3 Claims. (Cl. 208-22) This invention relates to a process wherein an initial solvent treatment is used for fractionating the liquid products obtained by the low-temperature pyrolysis of naturally occurring carbonaceous solids. It is particularly concerned with the initial selective solvent treatment oi primary low-temperature tar with aqueous methanol under selected conditions.

When naturally occurring carbonaceous solid fuels, such as bituminous coal and lignite, are `subjected to lowtemperature carbonization, i.e., at a temperature below 1400 F., the product tar is collected as a Vapor. Subsequent condensation of the vapors produces a highly viscous liquid tar product that is variously designated as primary, whole, unprocessed, unreiined, raw or crude tar. The term primary tar is ordinarily applied to tar obtained at low temperatures where a maximum yield of tar is obtained with a minimum of tar decomposition or alteration. These conditions represent an ideal state, and consequently no tar can be said to be entirely primary. As used herein, the terms primary, whole, and raw are considered essentially synonymous to indicate that substantially all of the low-temperature tar obtained `as a liquid product by condensation of the tar vapors is initially subjected to a solvent treatment process as described herein, and is not fractionally distilled prior to this solvent treatment. This tar product contains virtually all of the condensible ingredients of the carbonization vapors along with entrained inely divided particles of coal and partially carbonized coal. The recovery of valuable constituents contained in the tar is of considerable commercial importance. The process of this invention enables the recovery of these valuable constituents from low-temperature tar, whether derived from low rank noncoking coals, eg., lignite, brown coal and subbituminous coals, or from high-volatile highly caking coals, eg., Pittsburgh seam bituminous coal.

Where the tar is obtained by a low-temperature carbonization process under lluidized conditions, additional problems of recovery are presented. First, the finely divided particles oi coal and partially devolatilized coal contained in the fluidized low-temperature tar are unusually small in size and are present in greater quantity because of the attrition and entrainment caused by the turbulent conditions prevailing within a fluidized low-temperature carbonation processing vessel. Such tars may contain 25 percent or more by weight of nely divided particles of coal and partially carbonized coal. Second, the tars obtained from uidized low-temperature carbonization processes tend to be of a more primary character, i.e., the tar constituents tend to be closely related in structure to the constituents of the coal that is carbonized because there is little opportunity for cracking the constituents prior to recovery. Hence these tars tend to be more viscous than other types of low-temperature tars.

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Various techniques and plans have been proposed for processing primary tar for recovery of the valuable liquid constituents therein. All of these plans suffer from certain drawbacks. In some, operability is achieved at the expense of signicant tar yield. In others, fractional distillation of the tar, reducing its primary character, results in the cracking of the more Valuable constituents to yield less valuable constituents that may be obtained more economically from other sources. In still other methods, relatively expensive solvents are required in large volumes in treating the tar in order to avoid gumming and plugging of equipment and associated operability problems. in yet others of these plans, attempts have been made to iirst remove finely divided particles present by use of conventional mechanical separation techniques such as filtration, centrifugation and settling. Such techniques have been generally found lacking with respect to operability and commercial feasibility, particularly where a high percentage of solids is present in the tar. In general, the foregoing plans either introduce additional processing steps that are frequently costly and hence of laboratory interest only, or significantly alter the basic characteristics of the tar, whereby a lesser amount of valuable liquid products is recovered.

Fractional distillation has been principally used heretofore to eiect an initial fractionation of the primary tar. By topping of the tar, the more volatile tar acid oils may be recovered therefrom as an overhead distillate. However, depending on the nature of the tar and the thermal treatment, many of the tar constituents may polymerize, decompose or be carbonized. As a consequence, valuable liquid constituents present are lost by conversion to simpler hydrocarbons of less value or to coke.

Because ofthe highly complex chemical composition of primaiy low-temperature tar, the initial treatment of the whole tar by selective solvent techniques to elect separation of the valuable constituents of the tar has been considered too diiiicult to be of commercial importance. Direct solvent treatment of the whole tar must overcome problems of high tar viscosity, poor miscibility ot the tar with most solvents, and prolonged period of contact required between the tar and solvent for corn plete extraction and separation of components, together with high solvent to tar ratios. Ordinarily, any inely divided solids present must first be removed to prevent plugging of the equipment. Emulsiiication and agglomeration occurring in the tar-solvent system further inter-v fere with operability. Also, the lack of selectivity of vari-V ous solvent systems used introduces the further problem of after-recovery of sought-for constituents from both the extract and the reject phases of the solvent system. In addition, solvent techniques suitable for high-temperature tar are not ordinarily applicable to low-temperature tar because of the considerably dierent physical and chemical properties. At present, then, no vsatisfactory technique of commercial utility is known vfor the initial solvent treatment of primary low-temperature tar. Where the low-temperature tar is produced under fuidized conditions, the problem of separation becomes even more diilicult.

' Accordingly, it is an object of the present invention to provide a process for the fractionation of primary tar free from the disadvantages heretofore known.

VIt is a further object tov fractionate tar by an initial Ei solvent treatment into useful acidic and neutral tar fractions.

It is yet another object to provide a method for the continuous countercurrent extraction of low-temperature tar obtained by the low-temperature carbonization of bituminous coal under iiuidized conditions.

In accordance with the broad aspects of this invention, a primary low-temperature tar is treated in a continuous countercurrent liquid-liquid extraction system, including one or more extraction zones, with an aqueous methanol solvent under critical extraction conditions to achieve operability whereby the tar is fractionated into acidic and neutral tar fractions.

The general use of wood alcohol for extracting oils from high-temperature coal tar at room temperature is known. See U.S. 1,327,271. However, the conditions required in the present process for the effective fractionation of primary low-temperature tar into acidic and neutral tar fractions are highly critical in order to achieve operability and fractionation of commercial importance. This solvent fractionation produces tar fractions having distinctive chemical properties and boiling ranges. For achieving effective continuous countercurrent extraction of primary low-temperature tar, the process has been found highly critical with respect to the following factors: contact conditions between the tar and aqueous methanol, aqueous methanol concentration, temperature range, pressure range, and maintenance of the methanol as continuous phase. To attempt to achieve somewhat comparable results in a batch process would require use of excessive solvent to tar ratios, long contact times, and prohibitive settling times. Also, it would be difficult to achieve a separation of the sharpness with respect to chemical properties and boiling ranges characterizing the acidic and neutral tar fractions obtained in the present process.

The process of this invention is generally suitable for the treatment of tars obtained by the pyrolytic decomposition of carbonaceous solids at temperatures below 1400 F. Such carbonanceous solids include all ranks of coal, such as bituminous, sub-bituminous, brown coal, lignite and the like. This process is uniquely adapted to the treatment of low-temperature tars obtained by the lowtemperature carbonization of bituminous coals, e.g., highvolatile caking bituminous coals, under iiuidized conditions. The resulting tars contain varying amounts of tinely divided solids and are ordinarily particularly difficult to treat without substantial loss of valuable constituents.

It is considered critical for the purposes of this invention that the aqueous methanol used as solvent contain from 55 to 95 weight percent methanol with the balance water. Aqueous methanol containing between 55 and 65 percent by weight methanol is preferred Where it is desired to maximize the content of tar acids in the acidic tar fraction and minimize the content of neutral oils in this fraction. At above 65 weight percent methanol concentration, substantially all the tar acid oils appear in the acidic tar fraction. Maximum operability and selectivity are obtained when the methanol concentration of the solvent is between 65 and 80 percent by weight. When the aqueous methanol contains less than 55 percent by weight methanol, emulsification occurs and phase separation becomes unobtainable. When the methanol concentration in the solvent exceeds 80 percent by weight, selectivity begins to fall off, with the acidic and neutral tar fractions becoming less sharply defined.

The achieving or" satisfactory contact between the solvent and tar is considered critical for obtaining satisfactory operability in a continuous countercuirent extraction process. Various systems are known for achieving continuous coun'tercurrent liquid-liquid extraction. For ex'- ample, a horizontal multistage contactor may be used with highly viscous liquids such as tars. In general, columns containing packing are to be avoided because of impedance to proper ow of the tar and interference with the maintenance of suitable phase separation. Because of the characteristics of low-temperature tar, it has been found that an extraction column using a rotating disk contactor is particularly suitable for obtaining the required continuous countercurrent extraction eliiciency while maintaining the required phase separation. By use of a rotating disk contactor column, a high plate etiiciency can be attained, thereby rendering the process commercially feasible inasmuch as only from 0.5 to 3 volumes methanol per volume of tar is required for efiicient countercurrent extraction while still maintaining the methanol as continuous phase.

Many types of columns have been used in liquid extraction processes, such as packed columns, spray columns, baliie columns, and perforated plate columns. However, but few of these columns are suitable for use with highly viscous tars. For the purposes of this invention, to achieve desired operability, an extraction column that has been found particularly suitable contains internal serrated rotating stirrers and stator plates to provide alternating mixing and settling sections whereby effective contact is obtained between the tar and aqueous methanol. Various rotating-shaft extraction columns are known and may be used. However, because of the physical characteristics of the low-temperature tar, it is preferred that the settling or calming sections of such columns be free from packing and thus be in unobstructed communication with the mixing sections. In operating the rotating disk contactor column, a rotor speed providing a peripheral disk velocity of between 0.5 and 5 feet per second is preferred. Where the rotor speed falls below the preferred range, there is poor contact between the tar and aqueous methanol with relatively low extraction eiciency. At higher speeds, emulsication occurs with consequent poor phase separation. An extraction efficiency obtained with from l0 to 20 sections is suitable. Elimination of packing in the calming sections has not been found to deleteriously affect plate efficiency. At the same time this eliminates interference with the ready transport of solids by the countercurrently tiowing liquids. Ease of transport is particularly important where there is a substantial amount of finely divided carbonaceous solids present in the tar.

The temperature at which contact occurs between the aqueous methanol and tar is critical in that temperatures below 40 and above 80 C. are unsuitable. Where the temperature in the column falls below 40 C., the tar becomes gummy, cannot be extracted, and plugs the column. As the temperature is raised above about 60, phase separation becomes poorer as a result of emulsification occurring, with consequent loss of efficiency. Above C., phase separation is substantially lost. In general, optimum results are obtained at a temperature between 40 and 55.

Because or" the low boiling point of the methanol and the critical temperature requirements, effective extraction is carried out at superatmospheric pressure, generally at a pressure of at least 30 pounds per square inch gauge (p.s.i.g.). Where the pressure falls below 30 p.s.i.g., there is a tendency for the methanol to boil, with consequent interference with phase separation. Pressures above about 60 p.s.i.g. do not provide proportionately improved operability and thus are not warranted.

For the purposes of this invention, to achieve the separation of the substantially whole tar into the sought-for acidic and neutral tar fractions, only a single solvent, namely aqueous methanol is used for effecting the initial fractionation. This fractionation is successfully achieved even where finely divided carbonaceous solids are additionally present in the tar. However, where an excessive amount of finely divided solids is present, these may be removed by agglomerating them by a prior solvent treatment of the tar, followed by filtration, as shown in U.S. 2,774,716.

In lieu of agglomeration and filtration, operability may be forced with a highly viscous heavily solids-laden tar by adding a methanol-insoluble high-boiling neutral oil to this tar. This oil acts as a diluent for the methanolreject phase of the tar, and also as a carrier for the solids present in this reject phase, thereby effectively increasing the fluidity of this phase. The diluent oil may be autogenously derived from the tar itself during the over-all process. i

For a more complete understanding of this invention, its objects, features and advantages, reference should be had to the accompanying drawings in which:

FIG. l is a schematic illustration of the process of fractionating primary tar by an initial aqueous methanol treatment into acidic and neutral tar fractions.

FIG. 2 is a fragmentary perspective View of a section of a preferred rotating disk contactor column for use in this process.

FIG. 3 is a schematic illustration of a preferred process for separating the primary tar into acidic and neutral tar fractions together with the further processingr of these fractions.

Referring to FIG. 1, low-temperature tar in a storage vessel 1 is fed, preferably under pressure, to the top of a pressurized rotating disk contactor column 2 through a valved conduit 3. Aqueous methanol contained in a storage vessel 4 is fed to the bottom of column 2 through a valved conduit 5. Both the downwardly fed tar and the upwardly fed aqueous methanol are preferably preheated to the extraction temperature used. A geared variable drive motor 6 connected to a rotor shaft 7 of the rotating disk contacter is used to control the rotor speed in the column. Mounted on rotor shaft 7 are rotor disks 3. These are arranged in alternating relation to stator plates 9, which are fastened to the inner Wall of column 2. The pressure in the system is measured by a gauge 10.

In a preferred embodiment, the aqueous methanol consisted of 65 weight percent methanol with the balance water, and its flow and that of the tar was regulated so that approximately 1.5 volumes of aqueous methanol was used for each volume of tar fed. The pressure Was maintained at 40 p.s.i.g. throughout the run. The extraction temperature was maintained at approximately 45 C. The temperature within column 2 was controlled by the combined use of Nichrome heating coils and the circulation of cooling Water through copper tubes surrounding the column (not shown). Throughout the run, the rotor .speed was held constant at 450 rpm., which corresponded to a peripheral disk velocity of approximately 1 foot per second. It was found that at this rotor speed both good dispersion and separation of the discontinuous tar phase were obtained, the aqueous methanol constituting the continuous phase. The tar feed rate and the methanol to tar volume ratio were controlled so as to prevent flooding of the column during the continuous counter-current extraction. The total duration of a typical run was approximately 6 hours. Y

Again referring to FIG. 1, the aqueous methanol extract is removed from the top of column 2 through a valved conduit 11 and fed to a distillation column 12. The tar reject phase is removed from the bottom of column Z through a valved conduit 13 to a flash still 14. The overhead distillate from flash still 14 is fed through a conduit 15 to join the aqueous methanol extract stream. The neutral tar fraction from still 14 is removed as a bottoms product through a conduit 16. The methanol of the extract phase is removed by distillation in column 12 as an overhead product through a conduit 17 and fed toV storage vessel 4 for reuse in the process. Make-up aqueous methanol of suitable concentration may be fed through a conduit 1S to vessel 4. The bottoms product from the methanol distillation, which consists of the acidic tar fraction, is removed through a conduit 19. The acidic tar fraction may also be further processed in the same still or elsewhere for removal of valuable tar acid constituents conv tained therein, as shown in FIG. 3. The neutral tar fraction may also be used directly for commercial purposes as .a low-oxygen-containing asphalt.

- In FIG. 2 is shown a fragmentary perspective view of a section of one type of rotating disk contactor column found suitable for the continuous countercurrent extraction of Whole low-temperature tar using aqueous methanol. Stator plates 20 are rigidly affixed to the inner shell 21 of the column. The rotor disks 22, attached to a shaft 23 and rotatable therewith, preferably have serrated edges. This shape was found to provide more efficient contacting between the whole tar and the aqueous methanol than more conventional smooth-edged disks. No packing is present within the column. A suitable column was made of stainless steel, 1 0-inch inside diameter, had a spacing of 2.5 inches between stator plates and included 27 stages of extraction compartments. This column was electrically heated, with an upper 4-foot section wound with Nichrome heating wire and also with copper tubing for the passage of coolant.

In FIG. 3 is illustrated the further processing of the acidic tar fraction and neutral tar fraction to obtain valuable products for use in commerce. The process in its initial stages corresponds to that illustrated in FIG. 1, and similar numerals have been used for corresponding parts in both figures. Referring to FIG. 3, the aqueous methanol extract from the top of column 2 is led by means of a valved conduit 11 to a fractionating still 24. As the temperature is gradually raised in this still, which is operated at atmospheric pressure, methanol is the rst product evolved. This may be fed by means of a conduit 17' to the aqueous methanol storage tank 4 for reuse in the process. A second selected higher-boiling fraction (tar acid oil) consists of the tar acids and neutral oils boiling between about 160 and 300 C. of which, as shown below, more than 50 weight percent boils above 300 C. Various processes may be used for refining this tar acid oil to recover the phenolic constituents therefrom. One such suitable procedure is shown in U.S. 2,666,796. Or if the upper boiling point of this second fraction is set at about 230 C., this fraction will consist principally of the low-boiling t-ar acids. The neutral oil and high-boiling tar acids will be collected together with the creosote fraction. This creosote fraction, which is the next fraction evolved, consists principally of both liquid and solid hydrocarbons and may contain appreciable quantities of the higher boiling tar acids. It has a continuous boiling range of at least 125 C. beginning at about 200 C. or higher. Creosote is principally used in the preservative treatment of wood structures as protection against attack by fungi, marine borers, or insects. The bottoms residue from lfractionating still 24 is designated as an acidic asphaltene or acidic pitch. This material may be used as a binding material or as a road and roofing surfacing agent, or may be further upgraded by treatment with Various chemicals such as oxygen, sulfur and chlorine.

The following distribution of tar components, in parts by Weight, was obtained in a typical run. Referring to FIG. 3, 100 parts by weight of tar, calculated on a solidsfree basis, Was fed through conduit 3 to column 2. The

methanol extract from the top of column 2 through conduit 11 contained 47.5 parts of tar.l 'The tar reject fed to still 14 contained 52.5 parts tar. An additionalv 5.2 partstar, obtained as an overhead distillation Vproduct from still 14, was fed through conduit 15 to still 24. The tar acid oil fraction, topped at 300 C., contained 24.2 parts; the creosote fraction contained 17.2 parts; and the acidic asphaltene residue amounted to 11.3 parts by Weight of the starting tar.

As further shown in FIG. 3, the neutral tar fraction residue obtained from flash still 14 is fed by means of a conduit 16 to a coker vessel 25 where this fraction is destructively distilled. Evolved gas and light oil constitute the rst fraction collected, and the light oil may be readily separated from the gas by condensation. The light oil is a low boiling distillate which contains small amounts of benzene, toluene and xylenes, the principal constituent being referred to as solvent naphtha. The

7 light oil may be used without further purification for solvent purposes. The next fraction which may be recovered is a heavier oil boiling above about 300 C. This oil finds particular utility as a low-oxygen content carbon black feedstock for yielding a high abrasion resistance carbon black. The bottoms residue recovered from Coker 25 consists essentially of coke and contains any iinely divided particles originally present in the tar. This material is suitable as a fuel for metallurgical and power generation purposes. The coking operation is preferably carried out under conditions which minimize coking of the neutral hydrocarbon liquid products.

The following examples, arranged in tabular form, further illustrate the process of this invention with respect to the conditions desired for its practice and the results obtained therein, but are not intended as limitations thereof.

Table 1.-Extraction Conditions and Extract Yield Table IL Extraction Conditions and Extract Yield Run N 5 7 8 Methanol concu., wt. percent 65. 73. 5 86 92. 5 Te C 40 40 40 4o Solvent/tar, vol lvol 1. 5 1. 5 1. 5 1. 5 Pressure, p.s.i.g 35 35 35 35 Extract yield, wt. pc 8 17. 5 32. 5 50 Table IIL- Analyses of Tar and of Acidic Tar Fractions (Runs l-4) [All analyses are on a solids-free tar basis] Ultimate Starting Run 1, Run 2, Run 3, Run 4, Analysis Whole Acidic Acidic Acidic Acidic rlar Extract Extract Extract Extract Table IV.-Analyses of T ar Fractions (Rans 5-8) [All analyses are on a solids-free tar basis] tionation of primary low-temperature tar by an initial solvent treatment using aqueous methanol under selected conditions. However, it is readily apparent that various modifications may be made without departing from the spirit of this invention. For example, in the subsequent distillation treatment of the acidic tar fraction, the tar acid oils may be distilled at various temperatures between 160 and 300 C. At lower boiling cuts, the creosote traction will be enriched with increasing amounts of neutral oils. Gther such modiiications will readily suggest themselves. Thus while this invention has been described with respect to specilic preferred embodiments, it is not to be limited by the illustrative examples given but its scope should be determined in accordance with the objects and claim thereof.

The embodiments of the invention in which an exclusive property or privilege is claimed are delined as follows:

l. An acidic tar extract consisting essentially of a portion of a low-temperature tar initially dissolved and extracted at a temperature between about 40 and 55 C. by a single solvent consisting of an aqueous methanol solution containing about to 70 weight percent methanol, said tar being obtained from the low temperature carbonization of bituminous coal, said extract containing about 80 to 95 percent by volume of tar acids and more than 50 weight percent or" said extract boils above 300 C.

2. An acidic tar extract consisting essentially of a portion of a lowetemperature tar dissolved and extracted at a temperature of 45 C. by an aqueous methanol solution containing weight percent methanol, said tar being obtained from the low-temperature carboni/tation of bituminous coal, said extract containing about 80 to 95 percent by volume of tar acids and about 54 percent by weight of said extract boiling above 300 C.

3. A two-phase liquid-liquid extraction process for the continuous countercurrent fractionation of primary lowtemperature tar into acidic and neutral tar fractions by an initial treatment of said tar with a single solvent consisting of aqueous methanol,

said tar being produced by the carbonization of highvolatile bituminous coal under iluidized conditions at a temperature below 1400" F. and containing finely divided particles selected from the class consisting of coal and partially devolatilized coal, comprising:

feeding said tar as a first liquid phase downwardly in a liquid-liquid extraction zone containing mixing sections,

Tar and of Acidic and Neutral Run 5 Run 6 Run 7 Run 'Ultimate Starting 8 .Analysis Whole Tar Acidic Neutral Acidic Neutral Acidic Neutral Acidic Neutral Extract Reject Extract Reject Extract Reject Extract Reject 8. 23 7. 2l 7. 78 7. 44 7. 97 7. 81 8. 16 7. 91 7. 74 s2. c2 78. 15 85. 12 79. s4 85. 85 s2. 93 se. 44 s3. 34 s6. 0e o. 9s 1.02 0. 98 1.10 0. 91 1.01 o. s4 1. o3 0. 9s 6. 8s 12. 52 4. es 1o. es 3. 73 7. 17 3.07 6. 54 3. 60 1. 29 1.10 1. 44 o. 94 1. 54 1. 0s 1. 49 1.17 1. 54

As may be noted from the data shown 1n Tables I and 65 feeding as initial single solvent for sald tar an aqueous II, the yield of extract increases with increasing temperature and with increasing methanol concentration of the aqueous methanol solvent. Also, as shown in T able I, tar acid concentration in the extract decreases With increasing methanol concentration. The ultimate analyses shown in Table 1V clearly demonstrate the significant diference in oxygen content obtained between the acidic extract and neutral reject tar fractions.

As has been described herein, an improved method 'nas been provided for the continuous countercurrent fracmethanol solution as a second liquid phase containing 60 to 70 weight percent methanol and the balance water upwardly in said zone in countercurrent relation to the tar direction While agitating said tar and aqueous methanol in said mixing sections to provide effective mixing therebetween and while maintaining said tar and aqueous methanol at a temperature between 40 and 55 C. at a pressure between 30 and 60 p.s.i.g. and the low-temperature tar as dispersed liquid phase in the aqueous methanol as continuous liquid phase, the feed rates of the 10W- temperature tar and aqueous methanol being regulated so that between 01.5 and 3.0 volumes of aqueous methanol are fed to said zone for every volume of said tar, whereby the two phases are separated into an aqueous methanol extract and reject,

recovering the aqueous methanol extract containing the acidic tar fraction from the upper end of said zone, and

recovering as aqueous methanol reject the remainder of said tar as the neutral tar fraction from the lower end of said zone.

UNITED STATES PATENTS Wittek June 26, 1923 Weindel Sept. 3, 1929 Fisher Mar. 9, 1937 Rex Aug. 26, 1952 Russell Apr. 10, 1956 Kulik Ian. 27, 1959 Grossberg Mar. 24, 1959 Foley Oct. 4, 1960 FOREIGN PATENTS Great Britain June 9, 1932 Gr'eat Britain Dec. 30, 1953 

1. AN ACIDIC TAR EXTRACT CONSISTING ESSENTIALLY OF A PORTION OF A LOW-TEMPERATURE TAR INITIALLY DISSOLVED AND EXTRACTED TO A TEMPERATURE BETWEEN ABOUT 40 AND 55*C. BY A SINGLE SOLVENT CONSISTING OF AN AQUEOUS METHANOL SOLUTION CONTAINING ABOUT 60 TO 70 WEIGHT PERCENT METHANOL, SAID TAR BEING OBTAINED FROM THE LOW TEMPERATURE 